Electron spin echoes of a photoexcited triplet: Pentacene in <i>p</i>-terphenyl crystals

Sloop, David J.; Yu, Hsiang-Lin; Lin, Tien‐Sung; Weissman, S. I.

doi:10.1063/1.442520

Cited by 126 publications

(110 citation statements)

References 11 publications

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“…These include pentacene, pyrazine, and 13 C 60 [7][8][9][10][11]. We here determine the suitability of using a functionalized C 60 molecule for this scheme.…”

Section: Fig 1 (Color Online) (A)mentioning

confidence: 99%

Entangling Remote Nuclear Spins Linked by a Chromophore

et al. 2010

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Molecular nanostructures may constitute the fabric of future quantum technologies, if their degrees of freedom can be fully harnessed. Ideally one might use nuclear spins as low-decoherence qubits and optical excitations for fast controllable interactions. Here, we present a method for entangling two nuclear spins through their mutual coupling to a transient optically excited electron spin, and investigate its feasibility through density-functional theory and experiments on a test molecule. From our calculations we identify the specific molecular properties that permit high entangling power gates under simple optical and microwave pulses; synthesis of such molecules is possible with established techniques. DOI: 10.1103/PhysRevLett.104.200501 PACS numbers: 03.67.Bg, 03.67.Lx, 31.15.EÀ, 33.40.+f Molecules are promising building blocks for quantum technologies, due to their reproducible nature and ability to self-assemble into complex structures. However, the need to control interactions between adjacent qubits represents a key challenge [1][2][3][4]. We here describe a method for optical control of a nuclear spin-spin interaction that presents several advantages over conventional NMR quantum processors: the spin-spin interaction can be switched, the gates are faster, and the larger energy transitions facilitate polarization transfer onto the nuclear spins. After explaining the theory behind our method, we present an experimental study of a test molecule, and show with density-functional theory that an entangling gate could be achieved.We consider two nuclear spin qubits labeled n and n 0 and one mediator e. The mediator possesses a paramagnetic excited state jei with spin one character and a diamagnetic, spinless ground state j0i. The two nuclear qubits do not interact with each other directly, but both couple to the excitation via an isotropic hyperfine (HF) coupling with generally unequal strengths A and A 0 , see Fig. 1(a). The Hamiltonian in a magnetic field is given by (@ ¼ 1):where S z;i and S i are the Pauli spin operators and ! i denotes the respective Zeeman splittings (i ¼ n, n 0 , e). D is the zero-field-splitting (ZFS). ! 0 denotes the optical frequency corresponding to the creation energy of the excitation. Let us first analyze the case of a symmetric (homonuclear) system with ! n ¼ ! n 0 and A ¼ A 0 . Using degenerate perturbation theory and assuming that the electronic Zeeman splitting is much larger than that of the nuclei, ! n ( ! e and the ZFS, D ( ! e , we obtain an effective Hamiltonian by approximating H sym : ¼ hejHjei; thus,where V ¼ ðjc 1 ijc 2 i Á Á Á jc 12 iÞ is the matrix of the approximate eigenvectors up to first order and the E i (i ¼ 1; . . . ; 12) are the eigenenergies up to second order. This reveals that the time evolution of the entire system can be

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“…These include pentacene, pyrazine, and 13 C 60 [7][8][9][10][11]. We here determine the suitability of using a functionalized C 60 molecule for this scheme.…”

Section: Fig 1 (Color Online) (A)mentioning

confidence: 99%

Entangling Remote Nuclear Spins Linked by a Chromophore

et al. 2010

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“…This will provide us with the necessary basis to design suitable protocols for the controlled generation of nuclear spin entanglement for both these cases. In reality the functional groups are likely much larger than a single atom, but for simplicity we depict here only the two relevant atoms with a nuclear spin 1/2, for example, 13 C, 15 N, or 31 P. Note that the two satellites (or, rather, functional groups) are not necessarily both the same and that the system may thus be "asymmetric. "…”

Section: Modelmentioning

confidence: 99%

“…However, employing a mediator spin of the same kind as the qubit spins often does not allow for operation times that are many orders of magnitude shorter than the coherence time of the qubits. By contrast, many molecular structures possess transient optically excited triplet states (i.e., states with spin-1 character) that could be used as mediators for nearby nuclear spins [14][15][16][17][18]. In this article we show how fast controlled entangling operations with a high fidelity are possible in * erik.gauger@materials.ox.ac.uk suitable structures of this type.…”

Section: Introductionmentioning

confidence: 96%

Creating nuclear spin entanglement using an optical degree of freedom

2011

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Molecular nanostructures are promising building blocks for future quantum technologies, provided methods of harnessing their multiple degrees of freedom can be identified and implemented. Due to low decoherence rates, nuclear spins are considered ideal candidates for storing quantum information, while optical excitations can give rise to fast and controllable interactions for information processing. A recent paper [M. Schaffry et al., Phys. Rev. Lett. 104, 200501 (2010)] proposed a method for entangling two nuclear spins through their mutual coupling to a transient optically excited electron spin. Building on the same idea, we present here an extended and much more detailed theoretical framework, showing that this method is in fact applicable to a much wider class of molecular structures than previously discussed in the original proposal.

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“…Protons in the crystal were polarized under a low magnetic field of 0.09 T and at high temperature of 100 K. In order to achieve these "relaxed" conditions, a new polarizing method was employed. Firstly, electron population difference is produced among a triplet state of photo-excited aromatic molecules [7]. Then, this electron population difference is transferred to protons by so-called cross-polarization technique [8].…”

Section: P+ 68 He Analyzing Power Measurementmentioning

confidence: 99%

Elastic Scattering of Neutron-Rich Helium Isotopes from Polarized Protons at 71 MeV/A

Sakaguchi

Uesaka

Kawabata

et al. 2011

J. Phys.: Conf. Ser.

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Abstract. The vector analyzing power has been measured for the elastic scattering of neutronrich 6 He and 8 He from polarized protons at 71 MeV/A making use of a newly constructed solid polarized proton target operated in a low magnetic field of 0.1 T and at a relatively high temperature of 100 K. An optical model analysis revealed that the spin-orbit potentials for 6 He and 8 He are characterized by shallow and long-ranged shape compared with the global systematics of stable nuclei. Such a characteristics reflect a diffused density distribution of the neutron-rich isotopes.

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Electron spin echoes of a photoexcited triplet: Pentacene in p-terphenyl crystals

Cited by 126 publications

References 11 publications

Entangling Remote Nuclear Spins Linked by a Chromophore

Entangling Remote Nuclear Spins Linked by a Chromophore

Creating nuclear spin entanglement using an optical degree of freedom

Elastic Scattering of Neutron-Rich Helium Isotopes from Polarized Protons at 71 MeV/A

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